A convenient one-pot synthesis of substituted 2-pyrone derivatives

2-Pyrone derivatives were prepared in a one step procedure from readily available (chlorocarbonyl)phenyl ketene and 1,3-diketones such as 2,4-pentanedione, 1,3-diphenyl-1,3-propanedione, 1-phenyl-1,3-butanedione, 1,3-cyclohexanedione, 5,5-dimethyl-1,3-cyclohexanedione, 1,3-dimethyl-pyrimidine-2,4,6-trione and ethyl 2,4-dioxopentanoate. A mechanism is presented to account for the formation of the products. This method provides an easy route to prepare 3,4,5,6-tetrasubstituted 2-pyrones in good to excellent yields and in a short experimental time.     

Reactions of Bisazomethines of the Naphtalene Series with 1,3-Diketones

Bisazomethines prepared from aromatic dialdehydes and 2-naphthylamine were for the first time reacted with the following diketones: 1,3-cyclohexanedione, 5,5-dimethyl-1,3-cyclohexanedione, 5-phenyl-1,3-cyclohexanedione, indandione, and 2,2-dimethyl-1,3-dioxane-4,6-dione was studied. The reactions with 1,3-diketones of the cyclohexane series yield benzophenanthridine derivatives. The reactions with indandione, depending on conditions, give either bisarylideneindandiones or bisdihydrobenzo[f]indenoquinoline. As evidenced by the ^13C NMR and IR spectra, in the case of biphenyl-4,4'-dicarbaldehyde bis[N-(2-naphthyl)imine] and 2,2-dimethyl-1,3-dioxane-4,6-dione, 4,4'-bis(3-oxo-1,2,3,4-tetrahydrobenzo[f]quinolin-1-yl)biphenyl is formed.     

New Practical Synthesis of Tetrahydronquinolin-2,5-diones

A series of 4,6,7,8-tetrahydro-2,5-(1H,3H)-quinolinediones was prepared from ethyl-2-cyanoacetate, aromatic aldehydes and 1,3-cyclohexanedione or 5,5-dimethyl-1,3-cyclohexanedione by two steps, the yields were moderate to excellent. This method is a new practical promising green strategy to synthesize tetrahydronquino-lin-2,5-diones.     

Potassium fluoride-promoted reaction of (2-chloro-2-nitroethenyl)benzenes with 1,3-dicarbonyl compounds. A general synthesis of 6,6-dimethyl-2-nitro-3-phenyl-3,5,6,7-tetrahydro-4(2H)benzofuranones and some analogs

A convenient procedure to prepare in good yields 6,6-dimethyl-2-nitro-3-phenyl-3,5,6,7-tetrahydro-4(2H)-benzofuranones starting from (2-chloro-2-nitroethenyl)benzenes and 5,5-dimethyl-1,3-cyclohexanedione in the presence of potassium fluoride is reported. This method also proved efficient with other 1,3-dicarbonyl compounds, and has been successfully extended to 1,3-cyclohexanedione, 2,5-pentanedione, dibenzoylmethane and ethyl acetoacetate.     

Synthesis of N-substituted acridinediones and polyhydroquinoline derivatives in refluxing water

Acridinediones were synthesized by the one-pot Hantzsch condensation of an aromatic aldehyde, 5,5-dimethyl-1,3-cyclohexanedione, and aniline/4-methylaniline in re?uxing water. This method has then been extended to the four-component reaction of an aromatic aldehyde, 5,5-dimethyl-1,3-cyclohexanedione, ethyl acetoacetate and ammonium acetate for the synthesis of polyhydroquinoline derivatives. This is an environmentally friendly and efficient procedure providing good to excellent yields.     

在离子液体中4-芳基-5-氧代-1,4,5,6,7,8-六氢喹啉-3-羧酸酯的合成

以芳醛、氨基巴豆酸酯和5,5-二甲基-1,3-环己二酮或1,3-环己二酮为原料在离子液体[bmimBF₄]中合成了一系列4-芳基-5-氧代-1,4,5,6,7,8-六氢化喹啉-3-羧酸酯, 该方法具有产率高、环境友好等特点. 产物的结构通过红外光谱和核磁共振氢谱进行表征, 并通过X单晶衍射分析进一步证实产物的结构.     

水介质中5-氧代-4-芳基-1,4,5,6,7,8-六氢喹啉-3-羧酸甲酯的合成

在水介质中有三乙基苄基氯化铵(TEBA)存在下, 以芳醛、β-氨基巴豆酸甲酯、5,5-二甲基-1,3-环己二酮(或1,3-环己二酮)三组分混合反应, 一步合成了5-氧代-4-芳基-1,4,5,6,7,8-六氢喹啉-3-羧酸甲酯. 该反应具有操作简单、产率高、环境友好的优点.     

Synthesis and calming activity of 9-(4-<Emphasis Type="Italic">β</Emphasis>-D-allopyranosyloxyphenyl)-decahydroacridine-1,8-dione derivatives

Seven helicid derivatives containing decahydroacridine-1,8-dione were prepared via the reactions between 1,3-cyclohexanedione or 5,5-dimethyl-1,3-cyclohexanedione and the corresponding Schiff base. The structures of the helicid derivatives were characterized by IR, ¹H NMR, and HR-MS spectrum. The target compounds were evaluated by their hypnotic-sedative activity in vivo. The preliminary bioassay tests showed that some of the compounds had more potent activity than that of helicid.     

Green synthesis of tetrahydrobenzo[b]Pyrans by microwave assisted multi-component one-pot reactions in PEG-400

Polyethylene glycol is found to be a nontoxic and recyclable reaction medium for the microwave-assisted, multi-component one-pot reactions of aromatic aldehydes with ethyl-2-cyanoacetate and 1,3-cyclohexanedione or 5,5- dimethyl-1,3-cyclohexanedione in the presence of piperidine. This environmentally friendly microwave protocol offers ease of operation and enables recyclability of reaction medium and synthesis of a variety of substituted tetrahydrobenzo[b]pyran derivatives. It is an efficient, promising, and green synthetic strategy to construct tetrahydrobenzo[b]pyran skeleton.     

Application of carbenoid N-H insertion in the synthesis of the tricyclic 1,4-dihydropyrazines

The N-H insertion of the substituted anilines with 2-diazo-1,3-cyclohexanedione or 2-diazo-1,3-cyclopentanedione and subsequent cyclization enabled an efficient synthesis of a novel series of tricyclic 1,4-dihydropyrazines.     

Organocatalytic sequential one-pot double cascade asymmetric synthesis of Wieland-Miescher ketone analogues from a Knoevenagel/hydrogenation/Robinson annulation sequence: scope and applications of organocatalytic biomimetic reductions

A practical and novel organocatalytic chemo- and enantioselective process for the cascade synthesis of highly substituted 2-alkyl-cyclohexane-1,3-diones and Wieland-Miescher (W-M) ketone analogs is presented via reductive alkylation as a key step. First time, we developed the one-step alkylation of dimedone and 1,3-cyclohexanedione with aldehydes and Hantzsch ester through an organocatalytic reductive alkylation strategy. Direct combination of l-proline-catalyzed cascade Knoevenagel/hydrogenation and cascade Robinson annulation of CH acids (dimedone and 1,3-cyclohexanedione), aldehydes, Hantzsch ester, and methyl vinyl ketone furnished the highly functionalized W-M ketone analogues in good to high yields and with excellent enantioselectivities. Many of the reductive alkylation products show a direct application in pharmaceutical chemistry.     

Synthesis of steroids and related substances

Summary 3-p-Methoxyphenylcyclohexanone (II) was synthesized from 1,3-cyclohexanedione in three stages.     

The mechanism of 1,4 alkyl group migration in hypervalent halonium ylides: the stereochemical course

Rhodium(II)-acetate-catalyzed decomposition of either 1,3-cyclohexanedione phenyliodonium ylide or 5,5-dimethyl-1,3-cyclohexanedione phenyliodonium ylide in the presence of alkyl halides yields the corresponding 3-alkoxy-2-halocyclohex-2-enones via a 1,4 alkyl group migration shown to be concerted and intramolecular. In the case of (S)-alpha-phenethyl chloride, the rearrangement proceeds with essentially 88.6% retention of configuration. Theoretical calculations at the B3LYP/6-31G level reveal an activation energy of 5.4 kcal/mol for the process. A Claisen-like rearrangement occurs in the case where allylic halides, such as dimethylallyl or methallyl chorides, are used. The mechanistic pathway proposed for these processes involves addition of the halogen atom of the alkyl or allyl halide to the rhodium carbenoid from the iodonium ylide to yield a halonium intermediate that undergoes halogen to oxygen group migration. Aryl halides, such as chloro-, bromo-, iodo-, and fluorobenzene, behave differently under the same reaction conditions, yielding the product of electrophilic aromatic substitution, namely, the 2-(4-halophenyl) 1,3-cyclohexanedione.     

An improved electrochemical method for the synthesis of some benzofuran derivatives

Electrochemical oxidation of catechol and some 3-substituted catechols (1a--c) has been studied in the presence of 2-chloro-5,5-dimethyl-1,3-cyclohexanedione (3) in aqueous solution using cyclic voltammetry and controlled-potential coulometry. The results indicate that the quinones derived from catechols (1a--c) participate in a Michael addition reaction with 2-chloro-5,5-dimethyl-1,3-cyclohexanedione (3) with consumption of only two electrons per molecule of (1a--c) to from the corresponding benzoforans (10a--c). The electrochemical synthesis of benzofurans has been successfully performed at a carbon rod electrode and in an undivided cell with high yields and purity.     

Synthesis and antihelminthic action of 1,3-cyclohexanedione derivatives containing branched aliphatic chains

Summary 1,3-Cyclohexanedione was alkylated with branched allyl bromides. The resulting 2-alkyl derivatives and their enol acetates possess antihelminthic activity. The enol acetate of 2-(3,7,11-trimethyl-2-dodecenyl)-1,3-cyclohexanedione was found to be the most active.     

Condensation of Aromatic Aldehydes with Acidic Methylene Compounds without Catalyst

The condensation of aromatic aldehyde with isopropylidene malonate or 5,5-dimethyl-1,3-cyclohexanedione is carried out in DMF as solvent without catalyst.     

1H-1,2,4-Triazolo-5-diazonium salts in the synthesis of novel [1,2,4]triazolo[1,5-c][1,2,4]benzotriazin-6-ols

Chemistry of Heterocyclic Compounds - Condensation of 1H-1,2,4-triazolo-5-diazonium salts with 1,3-cyclohexanedione, accompanied by cascade processes of cyclization and oxidative aromatization,...     

氢化喹啉及其芳(杂)环稠合衍生物的合成

通过环己二酮与β-二腈基苯乙烯的Michael加成得到2-氨基-3-氰基-4-芳基-5-氧代-1,4,5,6,7,8-六氢喹啉(1); 4-苯基六氢喹啉(1a)与环己二酮发生胺的加成缩合反应生成2-N-(3-氧代-1-环己烯基)氨基-3-氰基-4-苯基-5-氧代-1,4,5,6,7,8-六氢喹啉(2), 在碱性和氯化亚铜催化下进一步环合成4-苯基-5-氨基-二-(2-氧代环己烷)并[b,g]-1,3-二氢萘啶(3). 芳醛、α-萘胺和环己二酮在乙醇中共回流, 则一锅法完成9-芳基-5,6,7,8,9,10-六氢苯并[c]吖啶酮(4)的合成. 对合成中所涉及的化学反应机理进行了尝试性的讨论. 新化合物1a～4c均经IR, ¹H NMR 及元素分析证明其结构.     

三组分串联反应一锅合成多环稠合的1,5-苯并二氮杂䓬化合物

以取代的邻苯二胺、1,3-环戊二酮或1,3-环己二酮(5,5-二甲基-1,3-环己二酮)、2,3-二羰基化合物为原料,无水乙醇为溶剂,对甲苯磺酸为催化剂,经2~5 h串联反应一锅合成43种新颖的1,5-苯并二氮杂?化合物,产率最高可达95%.该反应序列首先通过两次的亲核加成-脱水反应过程,形成分子内亚胺和烯胺结构的活性中间体,然后再经分子内的碳碳偶联环合-质子转移等过程,生成多环稠合的1,5-苯并二氮杂?目标化合物,实现了在一个反应体系中形成一个二氮杂七元环和四个新化学键(两个C—N,一个C=C,一个C—C).该方法操作简单,反应便捷,对环境友好,产率高,为1,5-苯并二氮杂?化合物的合成提供绿色环保,高效简便的合成思路.     

Control of Chemical Reactions by Using Molecules that Buffer Non-aqueous Solutions

Control of chemical reactions is necessary to obtain designer chemical transformation products and for preventing decomposition and isomerization reactions of compounds of interest. For the control of chemical events in aqueous solutions, the use of aqueous buffers is a common practice. However, no molecules that buffer non-aqueous solutions were commonly used. Herein, we demonstrate that 1,3-cyclohexanedione derivatives have buffering functions in non-aqueous solutions. It was also shown that these molecules can be utilized to alter and control chemical reactions. 1,3-Cyclohexanedione derivatives inhibited both acid- and base-catalyzed isomerizations and decompositions in organic solvents. The reaction products obtained in the presence of the buffering molecule 2-methyl-1,3-cyclohexanedione differed from those obtained in the absence of the buffering molecule. The use of buffering molecules that work in organic solvents provides a strategy to control chemical reactions and expands the range of compounds that can be synthesized.